Cam actuated machine



Aug. y26, 1941. o. R. HAAS CAM ACTUATED MAGHINE Filed May 10, 1939 Patented Aug. 26, 1941 CAM ACTUATED MACHINE Otto R. Haas, North Beverly, Mass., assignor to United Shoe Machinery Corporation, Borough of Flemington, N. J.,

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a corporation of New Jer- Application May 10, 1939, Serial No. 272,776

(AC1. i12- 220) 9 Claims.

The present invention relates to machines having oscillating work performing devices, and more particularly to improvements in cam driven actuating mechanisms for the stitch-forming devices of shoe sewing machines similar to those disclosed in prior U. S. Letters Patent of French and Meyer No. 473,870, dated April 26, 1892, and of the present inventor No. 2,037,722, dated April 2l, 1936, in which most of the stitch-forming devices are actuated by cams and oscillating cam actuated levers.

The objects of the present invention are to provide an improved machine of the type referred to which will operate at high speeds with less noise and for longer periods of time Without replacement or adjustment of the wearing parts than in previous machines of the same, type. When oscillating parts of a machine of this type are to lbe driven at high speeds, it is desirable to construct them with maximum strength and minimum weight. For this purpose, light-weight aluminum alloys are particularly useful. With machines of the type disclosed in the above patents, the cam actuated levers are fulcrumed on the machine frame and, at their free ends, certain of the ylevers are formed with gear teeth cut in the shape of curved racks or segments to mesh with driven toothed segments. If the toothed cam levers of the patented machines are composed of an aluminum alloy in an attempt to reduce the weight of the oscillating parts, the teeth at the ends of the levers do not resist properly the shocks and strains set up during operation of the machines. If the main body portions only of the levers are constructed of light weight alloy with the remaining toothed segmental portions of steel, the inertia of the levers is not materially reduced land the bulk of the weight is left at the free ends causing a pendulum action. Other objects of the invention, therefore, are to provide a novel and improved mechanism comprising a cam actuated lever having a gear toothed segmental portion for actuating a work performing device in the type of machine referred to, in which the advantage of light Weight alloy construction may be retained without sacrilcing durability in the gear toothed portion. A still further object of the invention is to provide an improved arrangement of a cam. and follower in a machine employing cams composed of synthetic resin material similar to those disclosed in inventors prior patent above identified which is effective in increasing the durability of the parts, and 1n providing a more accurate as metal cams heretofore employed.

lever is composed of light weight metal and the toothed segmental portion is rigidly joined to the main body. The use of synthetic resin in the segmental portion renders the lever at least as durable as a lever composed entirely of steel while Iat the same time the weight of the lever is reduced. The resin material on the segmental portion is lighter in weight than any metal or alloy heretofore employed in a cam lever, and when molded to the end of the lever, obtainsa rigid grip on the lever. Thus with decreased weight in the lever as a whole, through the use of an alloy, the lever may be made to oscillate more rapidly with resulting increased machine speed, and without imparting to the actuating cam or fulcrum of the lever undesirable or destructive strains.

The cams employed in the machine of inventors prior patent are composed of synthetic resin material and are formed in the same shape In order to insure free movement of Ia follower along the guiding groove in a metal cam, it is essential to select a follower roll which is smaller than the width of the cam groove. Wit-h the slightest variation of width in the cam groove, .a follower thus selected will-be looser in the wider portions of the groove than in the narrower portions so that an irregular movement may be imparted to the lever or other part on which the follower roll is mounted. Accordingly, one feature of the present invention relates to the provision in a machine having oscillating Work performing device-s, of a cam formed of synthetic resin material similar to that in inventors prior patent referred to, lbut cooperating with a follower of an external size which is as large or actually larger than the distance between the sides of the groove in the cam, the usual loose t to accommodate irregularities in the groove being rendered unnecessary. In actual practice it has been found that a tight t of the groove and follower causes no substantial loss of power, due to the greater resiliency of the synthetic resin material and'to the lower coeflicient of friction obtained with the use of this material" as compared with metal cams. Also, the tight initial flt after manufacture between the cooperating surfaces of the groove and follower results in a quieter operation and less frequent renewal than with the use of metal cams.

The several features of the invention will be clearly understood from the following description and accompanying drawing in which Figure 1 is a view in right side elevation of a portion of a sewing machine embodying the features of the present invention; and Figure 2 is a perspective view on an enlarged scale, partly broken away, of a toothed segmental portion of a cam lever illustrated in Figure l.

The machine illustrated in the drawing is a hook-needle outsole shoe sewing machine of a construction and mode of operation similar to that in the inventors patent, the hook-needle I of which is curved and secured to a metallic gear toothed segment I2 fulcrumed for oscillation at one end on a needle stud Il secured in the machine frame IE. The parts of the machine are necessarily heavier than practically any other class of sewing machines 0n account of the thickness and toughness of the materials operated upon. The stitch-forming devices of the machine are operated by elongated cam ac tuated levers. To simplify the illustration, the needle actuating lever I8 only is shown in full lines, while a portion ofthe awl lever, the curved awl and the awl segment are indicated in dotand-dash lines. During operation of the machine the lever I8 is oscillated on its fulcrum shaft 2D at the rear of the machine frame and the free end of the lever is formed with a curved gear toothed rack portion, the teeth of which mesh with the teeth of the needle segment I2.

To oscillate the cam lever in-the machine of the inventors prior patent, the lever has mounted on it at one side of4 its center line, a cam roll engaging a parallel sided groove in a cam formed 0f synthetic resin material. While a cam composed of this material has been found advantageous when used in combination with a driving and stopping mechanism for bringing the that part where the reduction of weight is most effective in decreasing the forces required to oscillate the lever. As a result, the reaction on the cam is lessened and the machine is rendered capable of operation at higher speeds than heretofore with less destructive wear inthe parts. Synthetic resin gear teeth on the lever I8 are comparable Ato steel in durability, and their use renders the lever much lighter at the free end and consequently further advantageous reduction in weight results if ,the main body of the lever I8 in the machine of the present invention is conposed of light weight metal alloy` containing aluminum. Such alloy also may conveniently be die cast to finished shape.

As has been stated, a further feature of the invention relates to those parts of the mechanism including the cam ^and the cam roll. The cam of the illustrated machine is composed of the same material as specified in inventors patent, and is indicated at 24. The cam is secured to a main sewing shaft 26 rotatable in the machine frame, the cam being formed by cutting as nearly as possible a parallel sided groove 28 of the proper shape to impart the desired movements to the needle I0. Fitting within the groove is a cylindrical cam roll 30 rotatable on astud 32 promachine to rest quickly and absorbing noises.,

incident to the use of cams in general, there may be difficulties encountered in the use of a cam composed of non-metallic material.

thetic resin material, a cam roll has been found to heat up and expand in size so that a closer t is obtained between the sides of the cam groove. As a result, minor irregularities in the cam groove tend to cause vibration in the lever on which the roll is mounted, even along a dwell portion of the came groove where no movement is being imparted to the lever. In case of certain of the actuating levers, such as that for actuating the needle, which lever/s have a curved gear toothed rack portion cooperating with a toothed driven segment, such vibration may cause undesirable chattering between the cooperating teeth of the parts.

According to a feature of the present invention, chattering and vibration between the cooperating teeth of the cam lever and needle segment are substantially reduced or eliminated, particularly when cams of synthetic resin are employed, by providing a curved rack portion or bar 22 on the lever I8 of synthetic resinmaterial similar. to the material from which the cams of inventors patent are made. The rack bar 22 is conveniently secured by molding to the lever I8. With the rack bar 22 sccured'to the lever I8 in place of the usual integral metal rack portion, the lever is 'substantially lightened in Due tov kthe lower heat conducting quality of the synroll along the groove.

jecting from one side of the lever IB. As a practical matter, there are small variations in width along the cam groove due to slight inaccuracies in machining, the widest and narrowest parts actually varying as much as several thousandths ofan `inch. Heretofore it has been the practice in the use of a metal cam to select a cam roll which is for each-inch of outside diameter, six or seven ten-thousandths oran inch smaller than the space between the sides of the cam groove at the narrowest part, and after assembly the machine ordinarily is run idly with an abundance of lubrication for several thousand rotations to insure against any tendency of the roll to bind within the cam groove during subsequent use of the machine. This so-called "running n of the machine causes a wearing away of the cam roll and groove so that a substantially greater difference exists between .the dimensions ofthe roll and the narrowest space between the sides of the cam groove than before assembly.

In the present invention, the cam roll 30 is so selected that during use ofthe machine the roll will be as large, or even larger; than the narrowest part of the cam groove, the resiliency of the resin material permitting passage of the Preferably, however, the roll`30 is originally selected with even a smaller dimension as compared with the cam groove than is the practice with metal cams, but due to the poor heat conducting quality of the resin material as compared with that of metal, the roll becomes quickly heated and enlarged to a size much greater than with the use of a metal cam.

weight-metal body portion and a gear ,toothed rack portion of synthetic resin material at its free end. Y v Y 2. vIn a machine of the type described having an operating camprovided, with a closed operating cam groove, the combination of a cam oscillated lever of light-weight metal alloy having a gear toothed racl: portion of'synthetic resin material.

n 3. A machine of ,the type described having, in combination, al work performing devicel a metallic gear toothed segment to which the work perhook needle, a metallic gear toothed segment to which the needle is connected, a cam, a cam roll actuated by the cam, and an oscillating lever having an elongated main portion of aluminum alloy on which the camlroll is mounted and a curved gear toothed rack portion of synthetic resin material arranged to drive said needle segment.

5. A machine of the type described having, in combination, a cam of synthetic resin material having a parallel sided groove cut into 'said material, and a cam follower comprising a metallic roll of an external size as large or larger than the width of the groove at its narrowest part whereby a tight operating Aiii; of the follower with kthe cam is maintained without objectionably increasing frictional resistance to the movement of the follower in the groove.

6. A machine of the type described having," in combination, a work performing device, a metallic gear toothed segment to which the work per-- forming device is connected, a cam' lever having an elongated light-weight metal alloy body portion and a curved gear toothed rack portion of synthetic resin material arranged to drive said segment, a cam of synthetic resin material, and a cam roll on the lever engaging a substantially parallel sided groove cut into the material of the cam, the size of the Jroll being as large or larger than the width of the groove in its narrowest part.

7.' A shoe sewing machine having, in combination, stitch forming devices including a needle and an awl, gear toothed segments for the needle and awl, levers at least one of which is provided with a gear toothed rack portion of synthetic resin arranged to drive one of said segments, a

cam of'synthetic resin material having a parallel sidedgroove cut into the material of the cam, and acam roll on the leverhaving the rack portion of synthetic resin engaging the groove in the cam.

8. A shoe sewing machine nation, work performing devices including a needle, and actuating mechanism for one of said devices including a cam of synthetic resin ma-v terial having formed therein a closed cam groove, a cam oscillated lever comprising a light-weight metal body portion and a gear toothed rack portion of synthetic resin material at its free end, a cam roll on the lever in engagement with the cam groove, and a gear toothed member engaging with said gear toothed rack portion for imparting a forward and back movement to said work performing devices.

9. A shoe sewing machine having, in combination, work perforating devices including a needle, and actuating mechanism for oneof said devices including av cam of synthetic resin material having formed therein a closed cam groove, 'a cam oscillated lever comprising a light-weight metal body portion, a cam roll on the lever in engagement with the cam groove, a member for imparting a forward and back movement to said work perforating device, and engaging rack portions n the free end of the Ilever and on said mem er, one of said rack portions being formed of synthetic resin material.

having, in combi- 

